Production of celluloid printing plates for use in the bichromate printing process



Dec; 15, 1925. 1,563.815

' H. REN

CK PRODUC N 0F CELLULOID PRINTING PLATES FOR US! THE BICHROMA'I'E PRIN G PROCESS 7 Filed Nov Eric ma'fel Zcciine J7 pen for Patented Dec. 15, 1925 I UNITED STATES PATENT OFFICE.

HEINRICH BENCK, 0] HAMBURG, GEBMiANY.

rnonuc'rron or CELLULOID rnmrme PLATES non ass in THE nronnoma'rn PRINTING rno'cnss'.

Application flIed November 4, 1924. Serial No. 747,868.

To all whom it may concern:

Be it known that 'I, HEINRICH RENCK, a citizen of Germany, and resident of Hamburg, Germany, have invented certain new and useful Improvements in or Relating to the Production of Celluloid. Printing Plates for Use in the Bichrom'ate Printing Process; and I hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it 'appertains to make and use the same- The invention relates to the production of celluloid printing plates for use in the bichroma'te printing process, a feature of the invention relating to the alteration in the surface condition of the celluloid plate to which a bichromated layer is subsequently applied.

The production of celluloid printing plates is known from the German patent to Carl Lorch, dated 16 September, 1898, No. 116252. Furthermore German patent to Gustav Koppmann, dated 18 January, 1901 No. 132696 describes a method of producing printing plates from celluloid according to which upon a celluloid plate coated with a layer of bichromated gelatin, pictures. are copied b "means of light, and developed, the cellulbid being then dissolved at those )arts of the bichromated layer which have een exposed by development.

But faultless printing plates cannot be produced by this method since in dissolving the celluloid by means of a celluloid solvent,

arts of the image produced b the e osure in the gelatine layer are lia le to come detached or disturbed whereby the roduced lines or points constituting part of t 1e printing surface become inclined, distorted or bent, so that a trueprinting block cannot be obtained. I

According to, the present invention a printing plate shown in the accompanying drawing suitable for practical work is obtained in the following manner:

The celluloid plate 1 is softened before being coated with bichromated latine 2, means of a suitable solvent or celluloi containin glacial acetic acid or equivalent, so that itiecomes spongy or softened on the surface, and on to this surface forming the interuniting sub-stratum layer 3 is then poured liquid gelatine to which has been added glacial acetic acid or equivalent and glycerine. In this way the gelatine combines with the celluloid in an intimate manner, and quickly sets- This gelatine layer is then chromated and the picture is copied thereon in the usual manner by photographic process with or without screens, and is then treated with a suitable solvent for the non-exposed gelatine and then subsequently with a suitable solvent for celluloid.

By means of this method the nonexp0sed portions of the gelatine are removed, while the exposed portion of the gelatine together with this support consisting of celluloid in intimate compound with'gelatine, are not attacked, but remain in the condition in which they were after the exposure and development.

A printing block suitable for use in practical working is thus obtained by the aforesaid method.

I claim- 1. The art of making celluloid printing plates, which comprises softening the surface of a celluloid plate by a suitable solvent, coating the softened surface with an aqueous solution of gelatine containing a softening medium for celluloid, bi-chromating the gelatine coating and exposing and developing the plate so made.

2. Theart of making celluloid printing plates, which comprises softening the sur: face of a celluloid printing plate and rendering it spongy by means of a solvent of celluloid, coating the surface of the plate with an aqueous solution of gelatine containing a celluloid solvent and a softener for gelatine, bi-chromating the gelatine coating after it has set, and exposing and developing the plate so made I 3. The art of making celluloid printing plates, which comprises softening the surface of a celluloid plate with acetic acid, coating the softened surface with an aqueous solution of gelatine containing glycerine and acetic acid, bi-chrdmating the gelatine after it has set, and exposing and developing the plate so made.

Dated this 6th day of June, 1924.

In testimon that I claim the foregoing as my invention I have signed my name hereto HEINRICH RENCK. 

